In an experiment, the length of an object is measured to be 6.50 cm. This measured value can be written as 0.0650 m.The number of significant figures on 0.0650m is
- 3
- 4
- 2
- 5
The Correct Option is A
Solution and Explanation
The correct answer is option (A): 3
Significant figures refer to the digits that carry meaning contributing to the precision of a number. The rules to determine significant figures are:
- All non-zero digits are significant.
- Zeros between non-zero digits are significant.
- Leading zeros (zeros before the first non-zero digit) are not significant.
- Trailing zeros (zeros after a decimal and a non-zero digit) are significant.
- In scientific (exponential) notation, only the number before the exponent counts for significant figures.
Given number: \( 0.0650 \)
- Leading zeros "0.0" are not significant.
- Digits "6", "5", and the trailing zero "0" (after decimal) are significant.
So, the number of significant figures = 3
Answer: Option (A) — 3 significant figures
Top Questions on Units and measurement
- The mass of an object is measured as \( (28 \pm 0.01) \) g and its volume as \( (5 \pm 0.1) \) cm\(^3\). What is the percentage error in density?
- MHT CET - 2025
- Physics
- Units and measurement
- The dimensional formula for RC is:
- CBSE CLASS XII - 2025
- Physics
- Units and measurement
- Choose the correct statements:
(A) Weight of a substance is the amount of matter present in it.
(B) Mass is the force exerted by gravity on an object.
(C) Volume is the amount of space occupied by a substance.
(D) Temperatures below 0°C are possible in Celsius scale, but in Kelvin scale negative temperature is not possible.
(E) Precision refers to the closeness of various measurements for the same quantity. Choose the correct answer from the options given below:- JEE Main - 2025
- Chemistry
- Units and measurement
The ratio of the power of a light source \( S_1 \) to that of the light source \( S_2 \) is 2. \( S_1 \) is emitting \( 2 \times 10^{15} \) photons per second at 600 nm. If the wavelength of the source \( S_2 \) is 300 nm, then the number of photons per second emitted by \( S_2 \) is ________________ \( \times 10^{14} \).
- JEE Main - 2025
- Physics
- Units and measurement
- Given below are two statements: Statement I : In a vernier callipers, one vernier scale division is always smaller than one main scale division. Statement II : The vernier constant is given by one main scale division multiplied by the number of vernier scale divisions. In light of the above statements, choose the correct answer from the options given below.
- JEE Main - 2025
- Physics
- Units and measurement
Questions Asked in WBJEE exam
- Let \( f(\theta) = \begin{vmatrix} 1 & \cos \theta & -1 \\ -\sin \theta & 1 & -\cos \theta \\ -1 & \sin \theta & 1 \end{vmatrix} \). Suppose \( A \) and \( B \) are respectively the maximum and minimum values of \( f(\theta) \). Then \( (A, B) \) is equal to:
- If \( a, b, c \) are in A.P. and if the equations \( (b - c)x^2 + (c - a)x + (a - b) = 0 \) and \( 2(c + a)x^2 + (b + c)x = 0 \) have a common root, then
- WBJEE - 2025
- Quadratic Equations
- If \( g(f(x)) = |\sin x| \) and \( f(g(x)) = (\sin \sqrt{x})^2 \), then:
- WBJEE - 2025
- Functions
- Which logic gate is represented by the following combination of logic gates?
- WBJEE - 2025
- Logic gates
- Ruma reached the metro station and found that the escalator was not working. She walked up the stationary escalator with velocity \( v_1 \) in time \( t_1 \). On another day, if she remains stationary on the escalator moving with velocity \( v_2 \), the escalator takes her up in time \( t_2 \). The time taken by her to walk up with velocity \( v_1 \) on the moving escalator will be:
- WBJEE - 2025
- Relative Motion
Concepts Used:
Units and Measurement
Unit:
A unit of a physical quantity is an arbitrarily chosen standard that is broadly acknowledged by the society and in terms of which other quantities of similar nature may be measured.
Measurement:
The process of measurement is basically a comparison process. To measure a physical quantity, we have to find out how many times a standard amount of that physical quantity is present in the quantity being measured. The number thus obtained is known as the magnitude and the standard chosen is called the unit of the physical quantity.
Read More: Fundamental and Derived Units of Measurement
System of Units:
- CGS system
- FPS system
- MKS system
- SI units
Types of Units:
Fundamental Units -
The units defined for the fundamental quantities are called fundamental units.
Derived Units -
The units of all other physical quantities which are derived from the fundamental units are called the derived units.